This invention relates to a device for closing tubular packages, whichxe2x80x94such as sausage endsxe2x80x94are gathered to a tress in the closing area, by means of a plastically deformable, in particular metallic closure clip, comprising a matrix and a tappet device which can be moved from a rest position, in which they are located outside the space occupied by the filled package, towards each other into an operative position at the tress, and comprising a magazine for supplying closure clips into the advance path of a tappet movable in the tappet device.
Such closing devices, which are usually disposed behind a filling machine for sausages or the like, are well known and have been quite successful. They are regularly provided in the vicinity of crimping elements which form the tress between two successive packages. As soon as the spreaders are spread and have formed the tress, matrix and tappet move towards the tress between the spreaders and close said tress by setting a closure clip; in fact generally by means of two closure clips set at a certain distance, so that between the same the adjacent packages can be separated from each other.
In the prior art, the respective closure clip(s) to be set is(are) usually supplied by the tappet device or by two such tappet devices. For this purpose, the magazine is attached to the tappet device, and due to the limited space between the spreaders (in which space the magazine which at least partly extends parallel to the filling direction cannot be introduced) such that at the drive end it opens into the guiding passage for the respective closure clip to be set and the associated tappet. This results in a correspondingly long advance path for the closure clip and a just as long advance path of the tappet, which in turn leads to a corresponding stroke of thexe2x80x94generally providedxe2x80x94closing cylinder; cf. for instance DE-A-20 54 348.
In the case of a mechanical drivexe2x80x94for instance by a cam platexe2x80x94the problem is the same, as is made clear by DE-A-1 123 588 (FIG. 4). In the case of a fluidic (generally pneumatic) drive, however, there is in addition a considerable consumption of air, because the size of the cylinder must be adapted to the force required for closing, but the required stroke only is a small part of the above-mentioned total stroke.
For the solution of this apparatus-related and operative problem, the invention providesxe2x80x94proceeding from the above-described devicexe2x80x94that the magazine is stationarily mounted and (only) in the rest position of the tappet device opens into the advance path of the tappet close to the closure clip outlet opening. In its rest position, the tappet device takes the closure clip required for the next operating cycle from the magazine and has it ready in the vicinity of its outlet opening. When the tappet device is subsequently moved towards the tress, the tappet only needs to make a short stroke, in order to fix the closure clip around the tressxe2x80x94by means of the opposing matrix. In the case of a pneumatic tappet drive, the closing cylinder can then be made correspondingly short and be operated in an air-saving way. Moreover, singling the closure clip and providing the same in the vicinity of the point of attachment are already effected during the filling of the package to be closed subsequently, whereby operating time is saved correspondingly.
By way of precaution it should be noted at this point that instead of supplying and singling the respective closure clip at the tappet device, this might also be effected at the matrix; in closure clip technology it is known per se to make this arrangement such that a closure clip is provided in the matrix and is closed by the tappet upon inserting the tress. In the case of this xe2x80x98kinematic reversalxe2x80x99, the magazine would have to be stationarily mounted such that in the rest position of the matrix it would be close to its holder for a closure clip; a corresponding mechanism would then be responsible for delivering the singled closure clip to the matrix. The above-described design is, however, preferred.
In general, the feed of the tappet in the tappet device will be effected by means of a fluidically actuated closing cylinderxe2x80x94for instance a pneumatic cylinder. Then, the arrangement can advantageously be made such that in the rest position, by means of a short feed movement, the closing cylinder piston moves a closure clip from its feed position into a stand-by position. This represents the singling of the respective closure clip to be set. On the other hand, in order to keep the closure clip, which still remains in the magazine, in said magazine when the tappet device leaves the rest position, a retaining sheet is preferably disposed at the tappet device, which retaining sheet extends parallel to the path of movement of the tappet device and is shaped corresponding to the same.
To perform the short feed movement of the tappet for the purpose of singling the closure clip, an auxiliary cylinder piston of a smaller diameter, which is coaxial with the closing cylinder piston, is provided in accordance with an embodiment of the invention. What is correspondingly small is the amount of compressed air required for this singling and this movement into the stand-by position. The arrangement may be made such that the auxiliary cylinder piston urges on the closing cylinder piston by means of a piston rod, but is not firmly connected therewith. In this way, the closing cylinder piston is mechanically and operationally free from the auxiliary cylinder piston, and when compressed air is applied to the closing cylinder piston, said auxiliary cylinder piston is automatically returned to its starting position by the same air. The coaxial double-piston arrangement for the above-described long advance path, which is known from DE 37 05 829 C1, has nothing got to do with this.
As mentioned already, it is known in the prior art to effect the movement of the matrix and the tappet device towards the package tress by means of swivel movements, where one after the other first the matrix was swivelled towards the tress and then the tappet device was swivelled towards the tress and the matrix. The actuation was effected by a cam plate. In contrast to this, independently fluidically actuated cylinders are provided in accordance with the invention to effect the swivel movements. This provides for a flexible change of the control times for the closing operation depending on the kind of closure clips to be processed, the diameter of the package, the material of the package, etc.
It is furthermore advantageous to pivotally mount at the side of the matrix a guiding sheet for the tress, which is provided with a funnel-shaped incision, and to bias the same by means of a spring into a tilted position facing the tress with respect to the longitudinal axis of the matrix. When swivelling the matrix towards the tress, the tilted position of the guiding sheet compensates the deviation of the swivel path from the path of a longitudinal movement. The pivotal connection of the guiding sheet with the tappet device provides for the automatic tracking of the guiding sheet at the end of the swivel movement of the tappet device. To further secure the final relative position of the matrix with respect to the tappet devicexe2x80x94with the tress caught in the incision of the guiding sheetxe2x80x94it may furthermore be provided that in the operative position at the tress the guiding sheet engages in a slot in the tappet device.